Daily Inhalation Rate and Time‐Activity/Location Pattern in Japanese Preschool Children

Lack of data on daily inhalation rate and activity of children has been an issue in health risk assessment of air pollutants. This study aimed to obtain the daily inhalation rate and intensity and frequency of physical activity in relation to the environment in Japanese preschool children. Children aged four–six years (n= 138) in the suburbs of Tokyo participated in this study, which involved three days' continuous monitoring of physical activity using a tri‐axial accelerometer and parent's completion of a time/location diary during daily life. The estimated three‐day mean daily inhalation rate (body temperature, pressure, saturated with water vapor) was 9.9 ± 1.6 m³/day (0.52 ± 0.09 m³/kg/day). The current daily inhalation rate value of 0.580 m³/kg/day proposed for use in health risk assessment in Japan is confirmed to be valid to calculate central value of inhaled dose of air pollutants in five‐ to six‐year‐old children. However, the 95th percentile daily inhalation rate of 0.83 m³/kg/day based on measurement for five‐year‐old children is recommended to be used to provide an upper bound estimate of exposure that ensure the protection of all five‐ to six‐year‐old children from the health risk of air pollutants. Children spent the majority of their time in sedentary and light level of physical activity (LPA) when indoors, while 85% of their time when outdoors was spent in LPA and moderate‐to‐vigorous physical activity. The results suggest the need to consider variability of minute respiratory ventilation rate according to the environment for more refined short‐term health risk assessment.     

Domestic help and the gender division of domestic labor during the COVID-19 pandemic: Gender inequality among Japanese parents

The enduring COVID-19 pandemic has gradually transformed our everyday lives. This study focuses on changes in work and family arrangements, with particular focus on changes in domestic help, and examines its impact on the division of domestic labor. Using a social survey of work and the family conducted in November 2020 and May 2021, the results show that from January 2020 (pre-pandemic) to May 2021, approximately 40% of respondents experienced a reduced gender gap for housework and childcare, while a large gender gap is still observed in the absolute frequency of undertaking domestic labor. Some lifestyle changes triggered by the pandemic, such as an increase in the use of takeaways or delivery meals, and the expansion of working from home, are found to be able to contribute a shift toward more equal sharing of domestic labor. However, the fact that the access to such lifestyle changes is more common among those with a relatively high income or high educational background suggests that the lifestyle changes imposed by the pandemic may exacerbate class disparities in the gender gap in domestic labor. Furthermore, the results show that decreased kinship support results in a greater childcare burden being placed on women.     

Urban shade as a cryptic habitat: fern distribution in building gaps in Sapporo,northern Japan

Urban Ecosystems - Biodiversity conservation and restoration in cities is a global challenge for the 21st century. Unlike other common ecosystems, urban landscapes are predominantly covered by...     

Working mothers and sons’ preferences regarding female labor supply: direct evidence from stated preferences

We investigate the argument that men who are raised by working mothers develop a preference that is favorable toward working women and, consequently, are more likely to have working wives. We test this hypothesis using the Japanese General Social Surveys 2000–2003. We directly examine the responses to the opinion survey’s questions regarding appropriate gender roles. The estimation results indicate that men raised by full-time working mothers are less likely to support traditional gender roles. Those men are also less likely to believe in the negative impact of a mother’s working on her children’s development.      

In Search of Perfect Foresight? Policy Bias,Management of Unknowns,and What Has Changed in Science Policy Since the Tohoku Disaster

The failure to foresee the catastrophic earthquakes, tsunamis, and nuclear accident of 2011 has been perceived by many in Japan as a fundamental shortcoming of modern disaster risk science. Hampered by a variety of cognitive and institutional biases, the conventional disaster risk management planning based on the “known risks” led to the cascading failures of the interlinked disaster risk management (DRM) apparatus. This realization led to a major rethinking in the use of science for policy and the incorporations of lessons learned in the country's new DRM policy. This study reviews publicly available documents on expert committee discussions and scientific articles to identify what continuities and changes have been made in the use of scientific knowledge in Japanese risk management. In general, the prior influence of cognitive bias (e.g., overreliance on documented hazard risks) has been largely recognized, and increased attention is now being paid to the incorporation of less documented but known risks. This has led to upward adjustments in estimated damages from future risks and recognition of the need for further strengthening of DRM policy. At the same time, there remains significant continuity in the way scientific knowledge is perceived to provide sufficient and justifiable grounds for the development and implementation of DRM policy. The emphasis on “evidence‐based policy” in earthquake and tsunami risk reduction measures continues, despite the critical reflections of a group of scientists who advocate for a major rethinking of the country's science‐policy institution respecting the limitations of the current state science.     

Risk Assessment of the Carbon Nanotube Group

This study assessed the health risks via inhalation and derived the occupational exposure limit (OEL) for the carbon nanotube (CNT) group rather than individual CNT material. We devised two methods: the integration of the intratracheal instillation (IT) data with the inhalation (IH) data, and the “biaxial approach.” A four‐week IH test and IT test were performed in rats exposed to representative materials to obtain the no observed adverse effect level, based on which the OEL was derived. We used the biaxial approach to conduct a relative toxicity assessment of six types of CNTs. An OEL of 0.03 mg/m³ was selected as the criterion for the CNT group. We proposed that the OEL be limited to 15 years. We adopted adaptive management, in which the values are reviewed whenever new data are obtained. The toxicity level was found to be correlated with the Brunauer‐Emmett‐Teller (BET)‐specific surface area (BET‐SSA) of CNT, suggesting the BET‐SSA to have potential for use in toxicity estimation. We used the published exposure data and measurement results of dustiness tests to compute the risk in relation to particle size at the workplace and showed that controlling micron‐sized respirable particles was of utmost importance. Our genotoxicity studies indicated that CNT did not directly interact with genetic materials. They supported the concept that, even if CNT is genotoxic, it is secondary genotoxicity mediated via a pathway of genotoxic damage resulting from oxidative DNA attack by free radicals generated during CNT‐elicited inflammation. Secondary genotoxicity appears to involve a threshold.     

WRN's tenth anniversary

Werner syndrome (WS) is a segmental progeroid syndrome in which patients display pleiotropic features of aging seen in the normal population. The advent of positional cloning in the 1990s markedly accelerated the identification of human disease-causing genes. In 1996, mutations in WRN, which was shown to encode a new, putative member of the family of RecQ DNA helicases, were identified in four patients as the cause of WS. Ten years after the identification of WRN, what have we learned about its role in WS, and its contribution to normal aging?